In my aim to simplify and aggregate my life, one gadget has had an enormous impact, meet CardNinja.

Card Ninja is effectively a wallet replacement that attaches to the back of your phone. I use it on the back of my iPhone but it works on virtually any smartphone.

It’s a pretty magical little gizmo. Irrespective of the number of items you include in it, it manages to hold your cash and cards in there no problem. I’ve had as many as ten cards, and a stack of cash (naturally) and it’s held it in there without issue. Conversely, I’ve had just two cards in there and no cash and it still manages to hold everything in there, even with a solid shake of the phone upside down. It really is very impressive.

To attach Card Ninja, you simple glue it to the back of your phone. It comes off fairly easily if you ever want to remove it, but you will need to hand pick bits of glue off the back of your phone — nothing too tiresome though, just a little time consuming — it does no damage to your phone.

CardNinja is also ideally sized so you don’t cover your phone’s camera, just make sure you attach it as far down your phone as possible.

The people I’ve shown it off to have some immediate concerns I’ll address here.

Cards falling out? Not a problem for me (or others), as mentioned above.

Losing both your phone, cash and money at the same time? Valid, but at least with Find My iPhone, Where’s my Droid and others, you stand a better chance of getting them all back than if you just lost your wallet somewhere.

Will it ruin my credit cards at all? I can say from almost a year of first hand experience that no damage has been done to any of my cards.

This might appear to be a near flawless ad-like mention of a product but the truth is I rarely get the time to write any more and when I do, it’s only for products that I’m in love with. This is one of them.

On face value, it might not appear to be the most glamorous, cool or cutting edge, but it is, however, incredibly useful and has proven to be the most used phone accessory I’ve ever owned.